Current controlling or regulating device



July 26, 1932. L. w. M CULLOUGH CURRENT CONTROLLING OR REGULATING DEVICEFiled Aug. 2, 1929 2 Sheets-Sheet IN VEN TOR A TTORNE Y y 1932- 1.. w.MCCULLOUGH 1,868,710

CURRENT CONTROLLING OR REGULATING DEVICE Filed Aug. 2, 1929 2Sheets-Sheet 2 Fig.6] m5 EqlE Fiqlfi 3: 1.3 s g I: 0

00 /20 2 J 4 5 6 INVENTOR TempC Dre-Seconds 2% ATTORNEY Patented July26, 1932 i I UNITED STATES PATENT OFFICE i w. uccunmuen, or Yonxnas,iron: cunanm oomaonnme on nneunarme nnvion I Application m an a, 1920.serial no. seam. i

The present invention relates to current of the electrolyte therebyproviding complete controlling or regulating devices and is more relation of the current. particular y directedtbward the control of heresistance elements may consist essencurrent flow incommercialpower andlighttially of a liquid containing cell or unithaving circuits (whichemploy motors, lig ts, ing one or more electrodes, dependingon theweldin outfits, and analogous translating design, immersed in a viscousliquid electro- 7 .devices by resistors havinga negative temlyte.Thecontainer may be one-of the elecperature coefllcient of resistance.trodes. v

It is known that the resistance of all They may be designed to absorba'consider- 7 lo metals and of practically all alloys increases ableportion of the line potential the instant 0 with the temperature, 1. e.such conductors the circuit in which they are connected is enhave apositive temperature coeflicient of ergized, and hence they will berapidly heated resistance'while the resistanceof carbon and by theenergy loss in the electrolyte. This 7 practically all electrolytesdecreases with inenergy loss brings about a rise in the tem erato creasein temperature which gives them a ture of the electrolyte, vwhich inturn re uces negative temperature coefiioientof resistance. itsresistance on account of its having a nega- The temperature coefficientof metals is of tive temperature coeflicient ofresistance. such a valuethat the change in resistance Moreand more current flows throu h thewithin reasonable temperature limits has no cell until the parts havecome to a stab e consu application as a current regulating mediumdition, or until the current consuming device 7 Y and variableresistance has been obtained in is operating normally and the currentreguthe ast by causing a movement of parts lating resistance maybeshunted out withwhic varied the amount of resistance in use out causingany disturbance on the circuit, or

at any instant, or which varied thecontact reit may remain in circuitand have its temsistance of numerous elements comprising a peratureregulated. It will thus be seen that unit as a means of changing theoverall resuch units function automatically as current sistance as forexample in a carbon pile rheoregulators to the extent that they can bedestat. In the liquid resistance heretofore emsigned to limit theinitial flow of current to a ployed, the vnegative temperaturecoefiicient given value and permit a steadily increasmg 0 of resistanceof the electrolyte has not been currentto flow until in a predeterminedtime utilized, the usual method of control bein to the resistor hasfulfilled its function and can vary the area of 'contact surface of thee ecbe shunted from service whereu on it cools trodes and theelectrolyte so that the desired off or is artificially cooled to be inreadiness variation in the amount of resistance in the for anotheroperating cycle.

to circuit could be had. The followin are some of the advantages I have,however, discovered that in the use of the viscous 'quid resistorcontemplated of viscous liquids as the electrolyte of a liqby thepresent invention: uid resistor, such a range in resistance is pos- 1.It has no moving parts and 1ts change sible within a convenient range intemperain conductivity is inherentm the reslstan ture that suchresistors afford a useful means itself. I

of regulating the flow of current in the circuit 2. It is strictlynon-inductwe. I in which they are connected. Such resistors 3. A unit ofgiven rating may be made 1n function as one way automatic currentregutvarious shapes to su1t particular reqmrelators or controllers inthat they permit a ments.

steadily increasing current to flow in the cir- 4. Units can be made msuch slzes as to cu t in which they are connected by virtue have anydesired hot or coldcurrent rat ng. of the temperature rise brought aboutby the with a current control range of at least 8 to 1 energy loss inthe electrolyte. They can be within a temperature range of 20 C. to madeto decrease the current flow in thejcir-' C. mo

cuit by artificially lowering the temperature 5. The available VISCOIIShqurd electrolytes acteristic resistor and include so-called non-freezesolutions such as lycerine and ethylene glycol, hence freezingtemperature is not detrimental in the operation of these resistors. Itmerely 1ncreases the time interval required to reach a desired value ofcurrent over what it would be with a higher initial temperature.

6. It regulates the starting current of motors, permitting a smallinitial current which builds up rapidly without interruption until themotor is running at full speed. This method of starting motors ispreferred over the use of a starting compensator, fixed resistances orso-called cross the line starters which allow sudden changes of currentof considerable magnitude with attendant annoyance due to flickering oflamps supplied from the same or adjacent circuit. This method ofstarting motors also eliminates vibration and shock caused by starterswhich permit abrupt changes in the starting current.

7. It embodies a new type of current controller wherein the flow ofcurrent may be regulated by controlling the temperature of theelectrolyte.

8. It may be used as extremely sensitive elements for determiningtemperature changes by measuring the change of resistance.

Where automatic variable resistors of the type contemplated by thepresent invention are employed for motor starting, the present inventionalso contem lates the provision of suitable means where y theelectrolytic resistor may be shunted after the motor has started so thatfurther energy loss in it may be avoided, and so that it'may cool offeither naturally or with the assistance of artificial means, so as to beready for the next motor starting operation. The accompanying drawingsdiagrammatically illustrate a type of cell which may be employed as anautomatic variable charshow several forms of motor connections by whichsuch a resistor may be employed to control the starting current in acurrent consuming device, such as a motor.

In these drawings:

Figures 1 and 1a are side elevational and end views of one formofresistor;

Figures 2 and 2a are side elevational and plan views of a modified formof resistor having radiating fins;

Figure 3 15 a diagrammatic view showing the resistor with artificialcooling means;

Figures 4 and 4a are views similar to Figures 1 and 1a showing theresistor arranged for circulating the electrolyte;

Figure 5 is a circuit diagram illustrating a motor with an automaticvariable resistance for starting purposes, together with a thermalelement to actuate a switch which short circuits the resistor andmaintains the shunt connection while the circuit is ener gized;

Figure 6 is a view similar to Figure 5 showing a modified form ofthermal arrangement and including an enclosed mercury switch in lieu ofbare contacts;

Figure 6a is a fragmentary view of the mercury switch;

Figures 7, 7a and 7b'are circuit diagrams, end view and side viewshowing a centrifugal switch arrangement for short circuiting theresistor;

Figure 8 is a diagrammatic view illustrating the short circuiting of theresistor by a vane operated by air currents created while themotor is inoperation; Figure 9 is a circuit diagram showing a modified "thermalcircuit control;

Figure 10 is a circuit diagram illustrating the use of an electricallyoperated circuit breaker or contactor for short circuiting the resistorin cases where large currents are involved;

Figure 11 is a diagrammatic view illustrating the use of the resistorfor the speed control of a variable speed induction motor;

Figure 12 is a chart illustrating typical resistivity-temperaturecurves; and

Figure 13 is a chart illustrating typical current-time curves.

While all viscous liquid electrolytes 'appear to have a relatively highnegative tem perature coeflicient of resistance as compared withnon-viscous solutions, better results seem to be obtained withelectrolytes miscible with water, such for example, as various sugarsolutions, as honey and molasses, and with glycols, such as ethyleneglycol and glycerine. Owing to the anti-freeze properties of ethyleneglycol and glycerine, the1r cheapness and uniformity of composition andstability under various conditions, these materials appear to give thebest results. They are miscible with water in all proportions and appearto be capable of being employed with a great ,many water soluble'andsolvent soluble salts, weak acids or alkalis.

-As representative of solutions 'of the wide variety which can beprepared employing the viscous liquids and electrolyte forming material,I have chosen, for purposes of illustration, the solutions of commonsalt in glycerine and ethylene glycol.

In Figure 12, are shown four resistivitytemperature curves. Thecoordinates start at the zero point of resistivity and temperature.Curve No. 1 shows the resistivity-temperature curve for a solutioncomposed of chemically pure glycerine with 1% saturated solution ofcommon salt. Curve No. 2 shows the resistivity of a similar preparationemploying 2% of saturated salt solution. Curve No. 3 indicates the sameconditions for a 3% salt solution. Curve No. 4 illustrates thereslstivity-temperature curve for a solution I sipating From the curvesfor the sodium chloride.

glycerine solution, it will be apparent that within a reasonable rangeof temperatures, say from room temperature up to 80 C. there isavailable a marked change in resistance. In the case of the ethyleneglycol solution, the change in resistance is very considerable andundoubtedly it will be found to be more marked were one to use a moreconcentrated solution of ethylene glycol than the commercial anti-freezesolutions available.

Figure 13 indicates the current-time characteristics of a particularresistor as determined when using solutions such as No. 3 and No. 4. Thevalues on the chart start at zero for both current andtime. From theseit will be apparent that it may take but a few seconds to heat up theelectrolyte to a suflicient degree to reduce its resistance to but asmall fraction of the resistance at room temperature.

Resistance units using viscous liquid electrolytes may be of varioussizes, forms and constructions depending on the conditions under whichthey are to be used, the time element required, the amount of current tobe controlled, radiation, etc. They may consist of any suitablecontainer, such as indicated at 10 in Figures 1 and 1a, having anelectrode 11 immersed therein. For convenience, the container is made ofconducting material and may constitute the other electrode of the unit.It will of course be understood that a number of plates, rods, pipes,

or other devices immersed in the liquid may be employed as electrodes.The container is preferably provided with a filling spout closed, orsubstantially closed, at the top as indicated at 12. One of theterminals is indicated at 13 as being connected to the case and theother at 14 goes through the case in an insulating bushing.

In Figures 2 and 2a, the container 10 is indicated as having a number ofradiating fins 15 for the purpose of more rapidly disthe heat generatedin the unit. i In Figure 3, the unit 10 is shown as being provided witha thermal element 16 such as a sylphon bellows, or the like which isadapted to actuate a valve 17 to control the flow of a cooling mediumabout the resistor.

In Figures 4 and 4a, the resistor 10'is indicated as being provided withpipe connections 18 through which the electrolyte may be circulated andexternally cooled.

The various forms of resistors described herein may be connected inseries with a current consumin device such as a motor wherein it isdesira is to control the inrush current. They may be made up in sealedcontainers or units and permanently associated with the load which theyare to control or may be placed elsewhere in the line as de- Figure 0,

sired. From the curves, it will be ap arent that when cold, theseresistors may very highresistance sufficient to materially limit theinrush of current.

Figures 5 to9 inclusive, show various connections for these resistanceswherein the resistor is short circuited after the apparatus has had timeto control the starting current ave a for the motor or load. In each ofthe figures, I

the'resistor is diagrammatically indicated by the reference letter R andfor convenience it is shown for use in a single hase motor or in thearmature current of a C. motor. It will, of course, be understood thatwhen used with polyphase circuits, additional resistors will beincorporated in the various legs of the circuit and the group will bedesigned to function as a multi-pole unit.

In Figure 5, the motor M is shown as being directly connected to theside L of the line and as being connected to the side L of the linethrough the resistor R. It is, of course, understood that the mainstarting switch for the motor is omitted from the drawings. In thearrangement shown in a thermal element 20 such as a thermal sylphon isdiagrammatically illustrated as being associated with two heating coils21 and 22. lVhen the sylphon element is cold, the heating element 22will receive current through the connections 24, 25 and 26. The heatingelement 21 will also receive current through the connections 27 and '26.The resistance element 22 is designed to have a lower resistance thanthe element '21 and is arranged to heat up the thermal element at such arate as to function the switch element 25 by the time the motor isbrought up to speed. This thermal element then operates the switch 25 toshort circuit the resistor B through the connections indicated at 28 and29. This will permit the resistor R to cool either naturally or to becooled artificially as desired. This movement will also disconnect theresistance element 22 from the circuit leaving the resistance element,21 in circuit. Element 21 is a low capacity heating element designed tomaintain the thermal element in the expanded position and maintain theshort circuit on the resistor R as long as the circuit is energized.

In Figure 6, the circuit arrangement is somewhat the same as in Figure5. The thermal element in this case, however, is a bi-metallicthermostat 20 carrying a mercury switch 25'. When the thermal element iscold, the mercury switch is in the dotted line position and the ingunits 21' and 22 are closed. The mercury switch is open in thisPOSltIQIl. Then the line is energized heating unlts 21 and 22immediately heat up the thermostat 20 which flexes and opens the on:-cuit of heating unit 22' in going td the posicircuits or both heattionwhich closes the mercu switch; In this position, the resistor is untedby the mercury switch through connections 31 and 32. The sustainingheating coil 21 kee s the thermostat hot which in turn keeps t e shortcircuiting switch closed while the motor is in operation. Y

In the form of con truction indicated in Figure 7, the resistor R isprovided with a shuntconnected to leads 36 and 37. This shunt is in theform of a centrifugal switch having .centrifu al elements such asindicated at 38 whic operate against a ring 39 to short circuit theresistors. This centrifmay be of any convenient t pe,

ugal switch lethe type commonly use as as for examp "a speed limitswitch for high speed ma- 40 adapted .chmes. 4

In the form of construction shown in Figure 8, the motor isprovided witha fan to blow air against a vane 41 whichoperates the circuit closer 42to shunt fixed contacts.

tactor 60 of any the resistor R.v This fan 40 may be a fan added to themotor or an air current for o erat' e ordinary windage of the motor orpulley.

In the arrangement shown in Fi ure 9, the resistor R is associated witha t ermal element 50 having a circuit closing member 51. When the partsare cold, the thermal element is collapsed, the short circuitingcontacts areopen. When it is heated up,

by the heating of the resistor R, the switch e ement 51 carried by thethermal element engages with three switch points indicated at 52, 53 and54. This short circuits the resistor B. through the connections 55,switch point 53, switch int 52 and con-.

nection 56.. It also estab ishes a circuit for the heating coil 57 of anauxiliary thermal v element 58 which soon expands and brings Thearrangements shown in Figures 5 to 9, inclusive, are more particularlyintended for fractional horsepower motors wherein the current tobe'controlled is small. Where, however, the resistor is to be used inconjunction with large motors, the kind of contacts shown in Figures 5to 9 may not be found satisfactory, and hence resort may be had to anarrangement such as shown in Figure 10 in which the resistor R is shortcircuited by an electricaldy operated switch or conesired capacity. Theoperthe vane may be obtained from 51 away from the' ating coil 61 isunder the control of the master contacts indicated at 62. These mastercontacts ma be connected to any of the devices indicate in Figures 5 to9 inclusive or closed by any other suitable means. I

Figure 11 illustrates the use of the resistors as a two-way currentregulator in av circuit arran' ement for controlling the speed of a wounsecondary variable speed induction motor. Here the collector rings forthree phase induction motor (supplied from leadsv L, L", and L) areindicated at 70, 71 and I 72. These rings are connected to separateresistor elements 7 4, 75 and 76 the viscous liquid electrolyte of thetype made up of above referred to. The resistance of these resistors maybe -maintained at a desired point by controlling the tem rature of theelectrolyte either by circulating the electrol te through an externalcooling coil or by irecting a cooling medium on the resistors. The speedof this type of motor is regulated by controlling the resistances in thesecondary or rotor circuits. I c

It will, of course, be understood that the resistance elements need notnecessarily disconnected from the circuit. They might, for example, bepermanently connected in series with an intermittently operated motorand the resistor would cool off, during the interval when the motor wasnot running, as.

electric refrigerator. would of course reduce the overall efiicienc .ofthe installation because there would e an energy loss in the resistors,but this would avoid the inrush of current to the motor which causes aflicker in house lighting circuits. I

It will also be understood that further variation of current may beobtained in the usual manner by varying the area'of contact ofelectrodesand electrolyte by either moving the electrodes-or regulatingthe volume 0 electrolyte.

What is claimed is:

1. The method of increasing the positive temperature coeflicient ofconductivity of an electrolyte which comprises mixing small quantitiesof the electrolyte with a non-conducting viscous liquid. s

2. The method of increasing the positive temperature coeflicient ofconductivity of an aqueous electrolyte which comprises mixing small.quantities of the electrolyte with a glycol. I

t .3. In combination with acommercial power or lighting circuit, aresistor comprising a liquid container, a viscous conducting liquidtherein having a negative temperature coeflicient vof resistance, andelectrodes imfor example in an Such an arrangement mersedin theelectrolyte, whereby all currentpassing through the resistor passesthrough the electrolyte and heats it, causing its resistance to lessenas the temperature rises and whereby substantial variat on in resistanceis available with fixed area of contact between the electrodes andelectrolyte.

4. The combination as claimed in claim 3 wherein the liquid containerserves as one of 5 the electrodes.

5. The combination as claimed in claim 3, wherein the conducting liquidis composed substantially of a viscous liquid to which an electrolytehas been added.

10 6. The combination as claimed in claim 3, wherein the conductinliquid is composed substantially of glycerme to which a small quantityof an electrolyte has been added.

u LEE W. MoCULLOUGH.

